package com.xzy.shop.web.servlet;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

@WebServlet
public class BaseServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //完成方法分配
        //1. 获取请求路径
        String uri = req.getRequestURI();
        //2. 获取方法名称
        String methodname = uri.substring(uri.lastIndexOf("/") + 1);
        //3. 获取方法对象
        try {
            //忽略访问权限修饰符，获取方法
            Method method = this.getClass().getMethod(methodname, HttpServletRequest.class, HttpServletResponse.class);
            method.invoke(this, req, resp);
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }

    /**
     * 直接将传入的对象序列化为json,并且写回客户端
     * @param obj
     */
    public void writeValue(Object obj, HttpServletResponse response) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        response.setContentType("application/json;charset=utf-8");
        mapper.writeValue(response.getOutputStream(), obj);
    }

    /**
     * 将传入的对象序列化为json,返回给调用者
     * @param obj
     */
    public String writeValueAsStream(Object obj, HttpServletResponse response) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(obj);
    }
}
